1. Field of the Invention
The present invention relates to a workpiece dividing method for dividing a workpiece such as a semiconductor wafer.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of crossing division lines called streets are formed on the front side of a substantially disk-shaped workpiece to thereby partition a plurality of regions where circuits such as ICs and LSIs are respectively formed. The workpiece is cut along the division lines to divide the regions where the circuits are formed from each other, thus obtaining individual semiconductor chips.
Cutting of the workpiece along the division lines is performed by using a cutting apparatus called a dicing saw, for example. In recent years, as another workpiece dividing method, a laser processing method using a pulse-shaped processing laser beam (pulsed laser beam) having a transmission wavelength to the workpiece has been carried out (see Japanese Patent No. 3408805, for example). In this laser processing method, the pulsed laser beam having an infrared region transmitting the workpiece is applied to the workpiece from one side thereof along the division lines in the condition where a focal point of the pulsed laser beam is set inside the workpiece, thereby continuously forming a modified layer inside the workpiece along each division line. Thereafter, an external force is applied to the workpiece, thereby dividing the workpiece along each division line where the modified layer is formed to reduce the strength.